1. Field of the Invention
The present invention relates to an encapsulant capable of collectively encapsulating a device mounting surface of a substrate on which semiconductor devices have been mounted, or a device forming surface of a wafer on which semiconductor devices have been formed on a wafer level, particularly to an encapsulant with a base for use in semiconductor encapsulation, a semiconductor apparatus manufactured by the encapsulant with a base for use in semiconductor encapsulation, and a method for manufacturing the same.
2. Description of the Related Art
Various methods have heretofore been proposed and investigated about encapsulation, on a wafer level, of a device mounting surface of a substrate on which semiconductor devices have been mounted (also referred to as a semiconductor device mounting substrate, hereinafter), or a device forming surface of a wafer on which semiconductor devices have been formed (also referred to as a semiconductor device forming wafer, hereinafter), and there may be exemplified by a method of encapsulating by spin coating or screen printing (Patent Document 1), and a method of using a complex sheet where a heat fusible epoxy resin has been coated on a film support (Patent Document 2 and Patent Document 3).
Among these, as a method of encapsulating a device mounting surface of a substrate on which semiconductor devices have been mounted on a wafer level, the following method has been used for mass-production; a film having adhesive layers on both surfaces is bonded to an upper portion of a metal, a silicon wafer or a glass substrate, or an adhesive is coated to the same by spin coating, etc., then, the semiconductor devices are arranged on the substrate, adhered and mounted thereon to form a device mounting surface, and the device mounting surface is then encapsulated by molding a liquid epoxy resin or an epoxy molding compound, etc., under a pressure and a heated condition (Patent Document 4). Also, as a method of encapsulating the device forming surface of a wafer on which semiconductor devices have been formed on a wafer level, a method of encapsulating the device forming surface by molding a liquid epoxy resin or an epoxy molding compound, etc., under a pressure and a heated condition is recently being used for mass-production.
According to the methods as mentioned above, encapsulating can be done at present when a small-diameter wafer of 200 mm (8 inches) or so, or a small-diameter substrate such as a metal, etc., is used without any big problems. However, when a large-diameter substrate on which semiconductor devices having 300 mm (12 inches) or more have been mounted or a large-diameter wafer on which semiconductor devices having the similar size have been formed is to be encapsulated, there is a big problem that the substrate or the wafer warps due to shrinkage stress of the epoxy resin, etc., at the time of encapsulating and curing. In addition, when the device mounting surface of the large-diameter substrate on which semiconductor devices have been mounted is encapsulated on a wafer level, the problem occurs that the semiconductor devices are peeled away from the substrate such as a metal, etc., by shrinkage stress of the epoxy resin, etc., at the time of encapsulating and curing, whereby there is a big problem that they cannot be used for mass-production.
As a method for solving the above-mentioned problems, for collectively encapsulating a device mounting surface of a substrate on which semiconductor devices have been mounted, or a device forming surface of a wafer on which semiconductor devices have been formed, there is a method of using an encapsulant with a base for use in semiconductor encapsulation having a resin-impregnated fibrous base in which a thermosetting resin is impregnated into a fibrous base and the thermosetting resin is semi-cured or cured, and an uncured resin layer composed of an uncured thermosetting resin formed on one surface of the resin-impregnated fibrous base (Patent Document 5).
When such an encapsulant with a base is used for semiconductor encapsulation, the resin-impregnated fibrous base having an extremely little expansion coefficient can suppress shrinkage stress of the uncured resin layer at the time of encapsulating and curing. Therefore, even when a large-diameter wafer or a large-diameter substrate such as a metal, etc., is encapsulated, a device mounting surface of a substrate on which semiconductor devices have been mounted can be collectively encapsulated on a wafer level while suppressing warp of the substrate or peeling of the semiconductor devices away from the substrate. Also, the encapsulant with a base for use in semiconductor encapsulation and has extremely high versatility and will be excellent in encapsulating properties such as heat resistance and humidity resistance after encapsulation.
A semiconductor apparatus using the above encapsulant with a base for use in semiconductor encapsulation has worse appearance than a conventional semiconductor apparatus using a thermosetting epoxy resin etc., for encapsulation because the surface of a base is exposed. Further, there is a problem in that a laser marking property is worse since the surface of the base is exposed.